Method of coating rubber with solventless crystalline polyolefin coatings

ABSTRACT

A novel laminate useful for seals particularly for vehicle window seals that are flexible, wear resistant and have a low coefficient of friction, is provided. The laminate comprises a rubber substrate and a polyolefin coating disposed on and adherent to the rubber substrate. The invention also provides novel methods of making laminates, particularly seals. Such method comprises the following steps: providing a rubber substrate; then applying a powdered crystalline polyolefin to the rubber substrate, in an amount sufficient to form a continuous layer when melted; and then melting the powdered crystalline polyolefin to form a continuous polyolefin coating disposed on, and adherent to, the rubber substrate. The invention also relates to seals comprising: an polyolefin rubber body; and a continuous coating of fused polyolefin disposed on and adherent to the rubber seal. Preferably the continuous coating of fused polyolefin is disposed in the glass run channel in the rubber body.

BACKGROUND OF THE INVENTION

[0001] Many vehicle seals are flexible to conform to vehicle glass toseal out the elements. The flexibility must be maintained over a widerange of temperatures. Moreover, the seal area in contact with glassrequires a low coefficient of friction so that when glass is raised orlowered, the seal does not stick to the glass. Whileethylene-propylene-diene monomer rubber (EPDM) has a suitableflexibility, it has a less than preferred coefficient of friction. In anattempt to reduce the coefficient of friction, the surface ofethylene-propylene-diene monomer rubber has been coated withpolyurethane. However, the polyurethane coating is not particularlyresistant to wear, which results in failure of the seal within arelatively short time. Attempts have been made to produce seals withpolymeric coatings other than polyurethane; however such seals typicallyemploy volatile organic solvents during the manufacturing process. Suchvolatile organic solvents have recently become the subject ofgovernmental regulation.

[0002] It would be desirable to have a flexible, wear resistant seal,having a low coefficient of friction, and which is applied withoutvolatile organic solvents.

SUMMARY OF THE INVENTION

[0003] The present invention provides novel laminate useful for seals,particularly for vehicle window seals that are both flexible and wearresistant and have a low coefficient of friction, preferably with aninitial coefficient of friction below 0.5. The laminate comprises arubber substrate and a polyolefin coating disposed on and adherent tothe rubber substrate.

[0004] The invention also provides novel methods of making seals; such amethod comprises the following steps: providing a rubber substrate; thenapplying a powdered crystalline polyolefin to the rubber substrate, inan amount sufficient to form a continuous layer when melted; and thenmelting the powdered crystalline polyolefin to form a continuouspolyolefin coating disposed on and adherent to the rubber substrate. Theinvention also relates to seals comprising: a polyolefin rubbersubstrate; and a continuous coating of fused polyolefin disposed on andadherent to the rubber substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005]FIG. 1 shows the laminate, composed of the rubber substrate andthe polyolefin coating disposed on the rubber substrate.

[0006]FIG. 2 shows an embodiment of a vehicle seal composed of therubber substrate and the polyolefin coating disposed in the glass runchannel.

[0007]FIG. 3 shows a another embodiment of a vehicle seal composed ofthe rubber substrate and the polyolefin coating disposed in the glassrun channel.

DETAILED DESCRIPTION OF THE INVENTION

[0008] Referring to FIG. 1 the coated substrate 10 is shown, which iscomposed to the rubber substrate 12 and the polyolefin coating 14.Referring to FIG. 2, a vehicle seal 110 is shown composed of rubbersubstrate, more specifically rubber body 112 and polyolefin coating 114disposed in the glass run channel 116. Referring to FIG. 3, a vehicleseal 210 is shown composed of rubber substrate, more specifically rubberbody 212 having glass run channel 216. The polyolefin coating 214 isdisposed on the channel face surface 218 of rubber body 212 andoptionally on the glass-contacting surfaces 224 and 226 of lip 220 andlip 222 of the rubber body 212. Glass G is shown in glass run channel216.

[0009] The coated rubber has an abrasion resistance preferably greaterthan 30 cycles/μm, more preferably greater than 100 cycles/μm, even morepreferably greater than 200 cycles/μm, most preferably greater than 300cycles/μm. The coating adheres well to the rubber. The coated rubber hasa coefficient of friction preferably below 0.5, preferably less than0.4, more preferably less than 0.3. Preferably the coefficient offriction is from 0.01 to 0.5, more preferably from 0.01 to 0.4, mostpreferably from 0.1 to 0.3.

[0010] The polyolefin coating preferably is preferably from 5 μm to 3mm, more preferably from 25 μm to 0.9 mm, in average thickness.

[0011] Forming the Polyolefin Coating on the Rubber Substrate

[0012] The method involves coating a rubber with a crystallinepolyolefin powder. The crystalline polyolefin powder is typicallyapplied by conventional application techniques, such as, for example, bysprinkling, by dipping, by powder-dropping from a continuous feederbelt; by electrostatic spray; by running extrudate through a powderfluid bed; by drawing down by applicator, or by a powder-coating gun.Alternatively, a rubber substrate emerging from an extruder is passedthrough a crystalline polyolefin powder—inert gas bed. The crystallinepolyolefin powder is applied to a rubber substrate, which substrate ispreferably at a temperature of from −40° C. to 315° C. and may beapplied to cured or uncured rubber substrate.

[0013] The layer of the crystalline polyolefin powder has an averagethickness greater than 5 μm. Once the crystalline polyolefin powder isapplied to the substrate, it is heated to melt and fuse the powder.Where the crystalline polyolefin polymer has a molecular weight ofgreater than about 3,000,000, the crystalline polyolefin powdertypically incompletely fuses upon heating, and the crystallinepolyolefin powder while still molten is preferably compressed by rollingsuch as with a glass or metal cylinder. However, during the rollingprocess care is to be taken to not shift the mass of heated polyolefincoating; such shift decreases the adhesion of the polyolefin coatingwhen the coated substrate is cooled.

[0014] Where the rubber substrate is not fresh, for example the rubbersubstrate displays bloom, it is preferable that the surface of therubber substrate is cleaned before applying the crystalline polyolefinpowder. The bloom is typically the result of components such as sulfur,stearic acid or anti-oxidants and the like, migrating to the surface ofthe rubber substrate. Conventional cleaning techniques are suitable.Good results have been obtained by abrading pre-vulcanized rubber, suchas with emery paper or by solvent cleaning such as by wiping withtoluene or mineral spirits or by both abrading and solvent cleaning.Where the surface is abraded, it is preferred that fine particulatesproduced by the abrading process be removed such as by rinsing. Goodresults have been obtained by using toluene. Air jets or water jets arealso suitable for such rinsing.

[0015] Where vehicle sealing strips are prepared by extrusion, thepolyethylene powder is preferably applied to the moving rubber extrudateafter it exits the extruder die, but before the rubber extrudate entersa curing oven. As the rubber extrudate is heated for curing, the powderfuses and adheres to the substrate rubber. An advantage of applying thepowder polyolefin to fresh rubber from the extruder is that the rubberdoes not require cleaning prior to the application of the powder.

[0016] Optionally, various textures, and colors are created in thepolyolefin coating. Optionally, conventional pigments are added to thepolyolefin coating prior to heating the coated substrate. Conventionalpigments such as for example titanium dioxide, carbon black, andconventional colored pigments are suitable. Optionally, texture isimparted to the polyolefin coating by varying the powder particles sizeand molecular weight of the polyolefin polymer. Larger particle sizesand higher molecular weights tend to produce rougher surfaces.Optionally, texture is imparted to the surface of the coating by using ablend of differing molecular weight polyolefin polymers or differenttypes of polyolefin polymers, such as for example a blend of LDPE andUHMWPE or LDPE and isotactic polypropylene. Optionally, texture isimparted to the surface of the coating by varying the amount ofcrystalline polyolefin powder initially applied to the rubber; areaswith greater quantities will provide bumps whereas areas having lesscrystalline polyolefin powder will produce valleys. Alternatively,smooth rollers or textured rollers are impressed into the warmpolyolefin coating to provide the polyolefin coating with a smoothsurface or a textured surface.

[0017] The Rubber Substrate

[0018] The rubber substrate is flexible and comprises an aliphatichydrocarbon polyolefin rubber. Preferably the polyolefin/aliphatichydrocarbon rubber is unsaturated, preferably having a diene content ofless than about 15 weight percent, preferably less than about 10 weightpercent. Preferably, the rubber is a conventional rubber such as used invehicle seals. Suitable rubbers are, for example, natural rubber, blendscomprising a thermoplastic, crystalline polyolefin polymer andvulcanized hydrocarbon rubber particles as described in U.S. Pat. No.4,130,534 to Coran, et al. issued Dec. 19, 1978; U.S. Pat. No. 4,130,535to Coran, et al. issued Dec. 19, 1978; U.S. Pat. No. 4,311,628 toAbdou-Sabet, et al. issued Jan. 19, 1982; U.S. Pat. No. 4,594,390 toAbdou-Sabet, et al. issued Jun. 10, 1986; U.S. Pat. No. 5,397,832 toEllul issued Mar. 14, 1995; and U.S. Pat. No. 5,290,880 to Moench, etal. issued May 1, 1994, synthetic polyisoprene rubber, polybutadienerubber, ethylene propylene diene terpolymer (hereinafter “EPDM”),ethylene propylene rubber(hereinafter “EPR”), butyl rubber, (hereinafter“IIR”), chlorobutyl rubber, (hereinafter “CIIR”) and bromobutyl rubber,(hereinafter “BIIR”) The rubber polymer in the rubber substratepreferably has a weight average molecular weight of 50,000 to 2,000,000,g/mole, more preferably from 80,000 to 500,000 g/mole, most preferablyfrom 100,000 to 300,000 g/mole.

[0019] The Crystalline Polyolefin Powder

[0020] The crystalline polyolefin powder comprises crystallinepolyolefin polymer. The crystalline polyolefin polymer has acrystallinity X_(c) of preferably from 20 wt. % to 100 wt. %, morepreferably from 30 wt. % to 100 wt. %, even more preferably from 40 wt.% to 100 wt. %, most preferably from 40 wt. % to 88 wt. %, as estimatedfrom the density of the crystalline polyolefin polymer. Thus:$X_{c} = {100 \times \frac{\left( {{Ps} - {P\quad \alpha}} \right)}{\left( {{Pc} - {P\quad \alpha}} \right)}}$

[0021] where Ps is the density of the sample, Pa is the pure crystaldensity (1.000) and Pc is the pure amorphous density (0.85).

[0022] The crystalline polyolefin powder preferably has an averageparticle diameter of 600 μm or greater, and preferably 5 μm or greater.Preferably, the crystalline polyolefin powder particle size is from 5 μmto 600 μm, more preferably from 10 μm to 350 μm; most preferably from 90μm to 250 μm.

[0023] The crystalline polyolefin powder preferably has an maximumparticle size of 1 mm or less, and preferably 600 μm or less. Preferablythe maximum crystalline polyolef in powder particle size is from 10 to 1mm, more preferably from 15 μm to 600 μm, even more preferably from 20μm to 500 μm; most preferably from 25 μm to 300 μm.

[0024] The crystalline polyolefin powder preferably has a melt flowindex at 190° C. under a load of 2 kg, from 0.0 to 100 g/10 minutes,more preferably from 0.0 to 50 g/10 minutes, and even more preferablyfrom 0.0 to 25 g/10 minutes. The crystalline polyolefin powderpreferably has a melt flow index at 190° C. under a load of 5 kg, from0.0 to 200 g/10 minutes, more preferably from 0.0 to 100 g/10 minutes,and even more preferably from 0.5 to 50 g/10 minutes. The crystallinepolyolefin powder preferably has a melt flow index at 190° C. under aload of 21.6 kg, from 0.0 to 500 g/10 minutes, more preferably from 5.0to 250 g/10 minutes, and even more preferably from 10 to 100 g/10minutes.

[0025] The crystalline polyolefin polymer preferably has a melting pointgreater than 100° C. but less than the decomposition point of the rubbersubstrate.

[0026] The polyolefin polymer is preferably a homopolymer or copolymerof polypropylene or of polyethylene or mixtures thereof.

[0027] Where the crystalline polyolefin powder comprises polyethylene,the crystalline polyolefin powder comprises at least one high densitypolyolefin polymer, having a weight average molecular weight of 30,000to 10,000,000 g/mole, more preferably from 30,000 to 1,000,000 g/mole,even more preferably 100,000 to 600,000 g/mole, most preferably from200,000 to 400,000 g/mole.

[0028] As used herein, the term “high density polyethylene” meansconventional high density polyethylene polymers as well as conventionalultra-high molecular weight linear polyethylene polymers, and thus “highdensity polyethylene” as used herein includes linear polymers having adensity of 0.94 to 0.97, as well as linear polymers having a molecularweight of 3,000,000 or higher, and having a density of 0.93 or higher.

[0029] As used herein, the term “low density polyethylene” meansconventional low density polyethylene polymers, as well as conventionalmedium density branched polyethylene polymers, and thus “low densitypolyethylene” as used herein includes branched polyethylene polymershaving a density of 0.915 to 0.93, as well as branched polyethylenepolymers, having a density of 0.89 to 0.94.

[0030] High density polyethylene polymers having molecular weights above3,000,000 tend to produce coatings which are incompletely fused and donot adhere well to the substrate. Preferably a second polyethylenepolymer is therefore added to such ultra high molecular weightpolyethylene polymer. Such second polyethylene polymer is either a lowdensity polyethylene polymer having a weight average molecular weight ofpreferably from 30,000 to 150,000 g/mole or a high density polyethylenepolymer having a weight average molecular weight of preferably from10,000 to 2,000,000 g/mole, more preferably from 30,000 to 150,000g/mole.

[0031] Where the polyolefin comprises polypropylene, the polypropyleneis preferably isotactic and preferably has a density from 0.880 to 0.92and a crystallinity preferably between 30% and 100% by weight.

[0032] In one preferred embodiment, the crystalline polyolefin powdercomprises a blend of crystalline polyolefin powders; specifically thecrystalline polyolefin powder comprises from 10 to 90 parts by weight ofa powdered high-density polyethylene polymer having a weight-averagemolecular weight between 200,000 and 10,000,000 g/mol., and 90-10 partsby weight of a powdered high- or low-density polyethylene polymer,having a weight-average molecular weight between 30,000 and 150,000g/mole.

[0033] In another preferred embodiment, the crystalline polyolefinpowder comprises a blend of crystalline polyolefin powders; specificallythe crystalline polyolefin powder comprises 25 to 75 parts by weight ofa powdered high-density polyethylene polymer, having a weight-averagemolecular weight between 250,000 and 6,000,000 g/mol., and 75 to 25parts by weight of powdered high density polyethylene polymer, having aweight average molecular weight between 40,000 and 150,000 g/mole.

[0034] Generally, where the crystalline polyolefin powder comprises onlyone crystalline polyolefin polymer, it is preferred that such polyolefinpolymer is a high density polyethylene having a weight average molecularweight of from 30,000 to 3,000,000 g/mole, more preferably from 100,000to 1,000,000 g/mole, even more preferably from 200,000 to 600,000g/mole, most preferably from 200,000 to 400,000 g/mole.

[0035] Polyolefin polymers having a molecular weight below 30,000 g/moletend to produce coatings displaying high wear rate, and are notpreferred.

[0036] Examples of crystalline polyolefin polymers suitable alone or ina blend to form the polyolefin coating are listed in Tables IA, IB and1C below. TABLE IA CRYSTALLINE POLYOLEFIN POWDERS HDPE Spectro- scopyHostalen Hostalen Coathylene Grade Hostalen GHR 8020 GUR400F HA 1931Hostalen MP*: GHR 8110 UHMW UHMW LDPE GUR X117 130- UHMWHDPE HDPE HDPEComposite UHMW HDPE 145° C. Property Ticona Ticona Ticona ParticlesTicona Aldrich MFI A — — 2 — — MFI B — 0.5 — — — — MFI C 0.8-1.6 14 <1<1 — Density 0.95 0.95 0.93 0.919 0.93 — (g/cm³) Crystal- — 130-135130-135 108-113 130-135 130-140 line melting range (° C.) Vicat — — — 87— — softening point (° C.) Number — — 32,000 — — avg. mw (g/mole) Weight600,000 300,000 more 730,000 4,400,000 — avg. mw than (g/mole) 6,000,000Max. <500 — 125 75 125 — particle size (d) micro- meters Mid- 120 210 c.60 17 c. 60 — range particle size Mesh — — — 200 — — size

[0037] TABLE IB CRYSTALLINE POLYOLEFIN POWDERS Coathyl- Coathyl-Coathyl- Coathyl- UHMW PE ene ene ene ene Treated NB6454 NC5374F HA2454HO1681 UHMW PE Surface HDPE HDPE LDPE* LDPE Property Aldrich AldrichClariant Clariant Clariant Clariant MFI A — — 8 20 7 70 MFI B — — — — —— MFI C — — — — — — Density 0.94 0.94 0.964 0.953 0.9244 0.916 (g/cm³)Crystal- 138 138 128-134 126-133 108-113 102-109 line melting range (°C.) Vicat — — 127 124 91 70 softening point (° C.) Number — — 25,00018,000 30,000 21,000 avg. mw (g/mole) Weight 3,000,000 — 80,000 60,00067,000 295,000 avg. mw - (g/mole) 6,000,000 Max. — — 90 125 75 630particle size (d) micro- meters Mid-range — 180 30 75 17 305 particlesize Mesh size — — 170 120 200 38

[0038] TABLE IC CRYSTALLINE POLYOLEFIN POWDERS MICRO- SCRUB 50Propyl-matte MDPE* HMW* Coathylene Coathylene 31 powder MP*: 109- LDPEPY0787F PB0580 PP 111 Micro homo-PP* homo-PP Micro Property AldrichPowders Clariant Clariant Powders MFI A. — — — — — MFI B — — 60 100 —MFI C. — — — — — Density 0.94 — 0.907 0.905 0.86 (g/cm³) Crystalline109-111 107-109 162-168 162-168 160-170 melting range (° C.) Vicat — —148 145 — softening point (° C.) Number avg. — — — — — mw (g/mole)Weight avg. — — — — — mw (g/mole) Max. particle — 297 200 90 31 size (d)micro- meters Mid-range — — 110 38 12 particle size micro-meters Meshsize —  50 70 170

[0039] The polyethylene polymer available as Vistomer HD 2800 fromComposite Particles Inc. is coated with a proprietary adhesive by themanufacturer and has a melt flow index at 190° C. under a load of 21.6kg, of less than 1 g/10 minutes, a density of 0.93 g/cm³, a crystallinemelting range of 130-135, a weight average molecular weight of more than6,000,000 a maximum particle size of 125 microns, a mid range particlesize of c.60 and a mesh size of 8,000. The Vistomer HD 2800 polyethyleneis less preferred particularly for use in a vehicle seal.

[0040] The following examples illustrate the invention and are notintended to be limiting.

[0041] The crystalline polyolefin powder was typically applied by one oftwo methods; by dipping or by drawing the crystalline polyolefin powderalong the substrate with a tool. The dipping method involved placing therubber substrate into the crystalline polyolefin powder to obtain about0.2 to 2 mm layer of the powder on the substrate. The crystallinepolyolefin powder was applied by dipping in Examples 3, 4, 6, 7, 18,20-25, 33, 40 and 41.

[0042] Alternatively, about 1 gram of crystalline polyolefin powder wasplaced near one end of a 20 cm×2 cm rubber strip. A notched tool wasused to draw down a strip of powder down the length of the strip. Thetool, made from a sheet of a high-hardness rubber had a notch 1 cm wideand 2 mm deep. The tool applied a strip of crystalline polyolefin powder2 cm wide and 1 to 2 mm thick and about 1 gram in weight, to the rubbersubstrate.

EXAMPLE 1

[0043] A coated substrate was prepared as follows. The surface of apiece of vulcanized, carbon black filled EPDM rubber wascleaning/roughening by abrading the surface by stroking the surfacesheet about 20 times with emery paper. Then the surface was scrubbedwith toluene for a short time and wiped dry. After a few minutes whenthe surface appeared to be dry by visual examination, the powder wasapplied.

[0044] The substrate was heated for 5 minutes at 230° C. in an aircirculating oven. Then a layer of polyethylene powder sold under thetrade name Hostalen GHR 8020 from Ticona, was applied by dipping therubber substrate into the powder to form a layer of powder approximately1 mm thick at the thickest points. The substrate was then placed in a230° C. oven for 5 minutes and removed and cooled.

EXAMPLE 2

[0045] A coated substrate was prepared as in Example 1, except thatafter the coated substrate was removed from the oven, a room temperatureglass cylinder or a steel cylinder was pressed and rolled over themolten polyolefin, by hand, for about 15 seconds. The cylinder was thenremoved; the resulting coated rubber was smooth and even.

EXAMPLE 3

[0046] A coated substrate was prepared as in Example 2, except thatabout one half the amount of crystalline polyolefin powder was used.

EXAMPLE 4

[0047] A coated substrate was prepared as in Example 3.

EXAMPLE 5

[0048] A coated substrate was prepared as in Example 2.

EXAMPLE 6

[0049] A coated substrate was prepared as in Example 1, except that thePolymatte 31 polypropylene was used instead of the GHR8020.

EXAMPLE 7

[0050] A coated substrate was prepared as in Example 6.

EXAMPLE 8

[0051] A coated substrate was prepared as in Example 2, except that theGURX117 polyethylene was used.

EXAMPLE 9

[0052] A coated substrate was prepared as in Example 1, except thatMicroscrub 50 polyethylene was used.

EXAMPLE 10

[0053] A coated substrate was prepared as in Example 1.

EXAMPLE 11

[0054] A coated substrate was prepared as in Example 2, except thatMicroscrub 50 polyethylene was used.

EXAMPLE 12

[0055] A coated substrate was prepared as in Example 2, except that amixture of 60% by weight of the Microscrub 50 polyethylene and 40% byweight GHR 8020 polyethylene was used.

EXAMPLE 13

[0056] A coated substrate was prepared as in Example 1, except that GHR8020 polyethylene was applied to an uncured substrate and thus notpre-cleaned.

EXAMPLE 14

[0057] A coated substrate was prepared as in Example 2, except that theGUR 400F polyethylene applied to an uncured substrate and thus notpre-cleaned.

EXAMPLE 15

[0058] A coated substrate was prepared as in Example 2, except thatGURX117 polyethylene was used.

EXAMPLE 16

[0059] A coated substrate was prepared as in Example 2.

EXAMPLE 17

[0060] A coated substrate was prepared as in Example 2, except that GHR8110 polyethylene was used.

EXAMPLE 18

[0061] A coated substrate was prepared as in Example 2, except that amixture of 60% by weight of the 8020 polyethylene and 40% by weight MS50polyethylene was used.

EXAMPLE 19

[0062] A coated substrate was prepared as in Example 2, except that amixture of 50% by weight of the 8020 polyethylene and 50% by weight MS50polyethylene was used.

EXAMPLE 20

[0063] A coated substrate was prepared as in Example 1, except that amixture of 50% by weight of the 8020 polyethylene and 50% by weight MS50polyethylene was used.

EXAMPLE 21

[0064] A coated substrate was prepared as in Example 1, except that amixture of 25% by weight of the 8020 polyethylene and 75% by weight MS50polyethylene was used.

EXAMPLE 22

[0065] A coated substrate was prepared as in Example 22.

EXAMPLE 23

[0066] A coated substrate was prepared as in Example 1, except that athin layer of an ultra high molecular weight polyethylene from Aldrichwas used.

EXAMPLE 24

[0067] A coated substrate was prepared as in Example 1, except that“high density polyethylene” spectroscopy grade 130-145° C. from Aldrichwas used.

EXAMPLE 25

[0068] A coated substrate was prepared as in Example 1, except that a“medium density polyethylene” melting point 109-111° C. from Aldrich wasused.

EXAMPLE 26

[0069] A coated substrate was prepared as in Example 2, except thatultra high molecular weight polyethylene from Aldrich was used.

EXAMPLE 27

[0070] A coated substrate was prepared as in Example 2, except thatultra high molecular weight polyethylene, having a treated surface, fromAldrich was used.

EXAMPLE 28

[0071] A coated substrate was prepared as in Example 2, except VistamerHD 2800 polyethylene coated with a manufacturer's proprietary adhesive,was used.

EXAMPLE 29

[0072] A coated substrate was prepared as in Example 1, except VistamerHD 2800 polyethylene, coated with a manufacturer's proprietary adhesive,was used.

EXAMPLE 30

[0073] A coated substrate was prepared as in Example 2, except that athe NC5374 Coathylene polyethylene was used.

EXAMPLE 31

[0074] A coated substrate was prepared as in Example 2, except that athe Coathylene NB6454 polyethylene was used.

EXAMPLE 32

[0075] A coated substrate was prepared as in Example 2, exceptCoathylene H01681 polyethylene with MFI of 70 was used.

EXAMPLE 33

[0076] A coated substrate was prepared as in Example 2, except thatCoathylene HA2454 polyethylene was used.

EXAMPLE 34

[0077] A coated substrate was prepared as in Example 2, except thatCoathylene HA1931 polyethylene from Clariant was used.

EXAMPLE 35

[0078] A coated substrate was prepared as in Example 2, except thatCoathylene PB0580 polypropylene from Clariant was used.

EXAMPLE 36

[0079] A coated substrate was prepared as in Example 2, except thatCoathylene PB0580 polypropylene from Clariant was used.

EXAMPLE 37

[0080] A coated substrate was prepared as in Example 2, except thatCoathylene PYO787 polypropylene from Clariant was used.

EXAMPLE 38

[0081] A coated substrate was prepared as in Example 2, except that amixture of 100 parts by weight of the 8020 polyethylene and 6.5 parts byweight molybdenum disulfide powder was used.

EXAMPLE 39

[0082] A coated substrate was prepared as in Example 1, except that amixture of 100 parts of the MS50 polyethylene and 6.5 parts by weightmolybdenum disulfide powder was used.

EXAMPLE 40

[0083] A coated substrate was prepared as in Example 2, except that amixture of 50% by weight of the MS50 polyethylene and 50% by weight GHR8020 polyethylene along with 6 parts molybdenum disulfide powder wasused.

EXAMPLE 41

[0084] A coated substrate was prepared as in Example 2, except that amixture of 25% by weight of the N6454 polyethylene and 75% by weight ofthe 8110 polyethylene was used.

EXAMPLE 42

[0085] A coated substrate was prepared as in Example 2, except that amixture of 25% by weight of the N5374 polyethylene and 75% by weight GHR8110 polyethylene was used.

EXAMPLE 43

[0086] A coated substrate was prepared as in Example 2, except that amixture of 50% by weight of the N5374 polyethylene and 50% by weight GHR8110 polyethylene was used.

EXAMPLE 44

[0087] A coated substrate was prepared as in Example 1, except that amixture of 50% by weight of the N6454 polyethylene and 50% by weight ofthe 8110 polyethylene was used.

EXAMPLE 45

[0088] A coated substrate was prepared as in Example 1, except that amixture of 75% by weight of the N5374 polyethylene and 25% by weight GHR8020 polyethylene was used.

EXAMPLE 46

[0089] A coated substrate was prepared as in Example 1, except that theGHR 8110 polyethylene was used.

EXAMPLE 47

[0090] A coated substrate was prepared as in Example 1, except that amixture of 25% by weight of the N5374 polyethylene and 75% by weight GHR8110 polyethylene was used.

EXAMPLE 48

[0091] A coated substrate was prepared as in Example 1, except that amixture of 38% by weight of the N5374 polyethylene and 62% by weight GHR8110 polyethylene was used.

EXAMPLE 49

[0092] A coated substrate was prepared as in Example 1, except thatN5374 polyethylene was used.

EXAMPLE 50

[0093] A coated substrate was prepared as in Example 1, except that amixture of 75% by weight of the N5374 polyethylene and 25% by weight GHR8100 polyethylene was used.

EXAMPLE 51

[0094] A coated substrate was prepared as in Example 1, except that amixture of 50% by, weight of the N5374 polyethylene and 50% by weightGHR 8100 polyethylene was used.

[0095] Comparative Example A

[0096] An EPDM rubber strip without a coating was used as a control.

[0097] Comparative Example B

[0098] An EPDM rubber strip with a Versicoat® polyurethane as coatingwas prepared using conventional methods.

[0099] Comparative Example C

[0100] A coated substrate was prepared as in Example 1, except that athin layer less than 300 μm of GHR 8020 polyethylene was used.

[0101] Evaluation

[0102] The coated rubbers of the Examples and the Comparative Examplewere evaluated for abrasion resistance, coefficient of friction andadhesion. After cooling, the test strips were tested by using thecrockmeter. The coefficient of friction was recorded as a function ofthe number of crockmeter cycles. The typical average thickness of thefilms prepared was about 20 mils (about 0.5 mm).

[0103] The durability of the samples was determined by test methodentitled General Motors Engineering Standards, Seals Abrasion ResistanceGM9909P:R1:ETSSLN, January 1993. The abrasion resistance was measured byusing the wear resistance testing apparatus, as shown in FIG. 1 of theGeneral Motors Standards. A 4 mm thick piece of non-tempered glasshaving a radius on the edge of 2.5 to 6 mm, with satin finish edge wasrubbed, under weight, back and forth across the coated substrate. Thesamples of the coated substrates of the examples, were cut to 200 mm inlength and trimmed as needed. The samples were mounted to a mountingfixture which was then attached to the wear resistance testingapparatus. The mounting fixture was centered and tighten so that themounting fixture remained stationary and straight during the test. Aweight of 2.7 kilograms was applied and the wear resistance testingapparatus was set to 60 cycles per minute, where the stroke of theabrasion element, that is, the glass, is 150 mm with one back and forthmovement as one cycle. The glass was loaded to the wear resistancetester as per profile print in FIG. 1 of the General Motors EngineeringStandards.

[0104] The wear resistance test was performed and the samples weretypically visually examined every 500 cycles. The glass was replacedevery 5000 cycles.

[0105] In addition to visual examination, the depth of wear wasdetermined by optical microscopy. Thus, the wear resistance is reportedas number of cycles per micrometer (micron). The results are presentedin Table II.

[0106] The coefficient of friction was determined by dividing lateralforce to move the glass by the normal force 2.7 kg. this was done foreach cycle and averages were taken. The polyolefin coatings of theExamples were evaluated for adhesion to the rubber substrate by visualexamination and manual examination. TABLE II SUMMARY OF CROCKMETER ANDWEAR RESULTS Depth of Abrasion Cycles Wear, Resistance Powder InitialAvg. To Coating micro- cycles/ Sample Type COF COF fail Appearancemeters micrometer Compara- Control 0.7027 0.6775 8640 None — — tive Ex._(—) Compara- Control 0.6584 0.62041 5000 None — — tive Ex. _(—)Compara- HS-37-EX-2 0.3093 0.4262 1314 — — — tive (Versicoat Ex. _(—)PU) Ex. 1 Hostalen 0.277 0.3461 16600 Moderately WT — GHR8020 heavy notrolled uniform, rough Ex. 2 Hostalen 0.3208 0.4351 3300 Medium WT —GHR8020 thick, rolled uniform, rough Ex. 3 Hostalen 0.4038 0.4497 430Light,  52  8.3 GHR8020 uniform, rolled rough Ex. 4 Hostalen 0.37140.3946 4835 Light to  75  64.5 GHR8020 medium, slightly rough Ex. 5Hostalen 0.3171 0.3455 5000 Medium to  59  84.7 GHR8020 heavy, rolledslightly rough Ex. 6 Polymatte 0.7354 0.7353 106 Moderate WT — 31 tothin, smooth Ex. 7 Polymatte 0.7758 0.7758 115 Moderate WT — 31 to thin,smooth Ex. 8 Hostalen 0.3168 0.4149 209 Medium WT — GURX117 thickuniform unfused Ex. 9 Microscrub 0.4663 0.515 244 Aesthetic- WT — 50ally not rolled mottled Ex. 10 Hostalen 0.2475 0.2823 20000 Thick, 153130.7 GHR8020 smooth, not rolled trans- lucent Ex. 11 Microscrub 0.44040.464 10000 Thick, WT — 50 smooth, rolled trans- lucent Ex. 12Microscrub 0.3657 0.3409 20000 Thick, 257  77.8 50/Hostalen smooth,GHR8020 trans- 60/40 lucent rolled Ex. 13 Hostalen 0.295 0.3061 20000Thick,  62 322.6 GHR8020# smooth, trans- lucent Ex. 14 Hostalen 0.24020.3186 20000 Smooth,  33 606.1 GUR400# white rolled film, poor adhesionEx. 15 Hostalen 0.3322 0.3889 6675 Smooth,  20 333.8 GURX117 whiterolled film; poor adhesion Ex. 16 Hostalen 0.3593 0.3229 20000 Thick,129 155.0 GHR8020 smooth, rolled trans- lucent Ex. 17 Hostalen 0.23710.255 20000 Thick,  31 645.2 GHR8110 trans- rolled lucent Ex. 18GHR8020/ .05321 0.34 10000 White,  43 232.6 Microscrub moderately 5060/40 thick rolled Ex. 19 Hostalen 0.4698 0.4563 4153 Moderately  96 43.3 GHR8020/ thin, Microscrub trans- 50 50/50 lucent rolled Ex. 20Hostalen 0.3814 0.4364 2334 Medium WT — GHR8020/ thin Microscrub rough,50 25/75 trans- not rolled lucent Ex. 21 Hostalen 0.3676 0.5592 1000Medium WT — GHR8020/ thin Micro- rough, scrub 50 trans- 25/75 not lucentrolled Ex. 22 Hostalen 0.4782 0.4928 6146 Medium WT — GHR8020/ thinMicroscrub rough, 50 25/75 trans- not rolled lucent Ex. 23 UHMW PE1.1185 1.0854 59 Very thin, WT — (Aldrich) milky white Ex. 24 HDPE0.4545 0.5719 246 Thin, WT — Spectroscopy smooth Grade trans- MP: 130-parent 145° C., (Aldrich) Ex. 25 Medium 0.5158 0.5588 2487 Medium WT —density PE thickness, (MDPE) trans- MP: parent 109-111, bumpy (Aldrich)Ex. 26 PE UHMW 0.4945 0.5439 121 Thick  32  3.8 (Aldrich) white rolledfilm, poor adhesion Ex. 27 PE UHMW 0.3007 0.3508 10000 Thick off-  34294.1 (Aldrich), white treated film, poor surface adhesion not rolledCompara- Vistomer 0.3976 0.4096 85 Smooth,  40  2.1 tive HD2800 thickEx. 28 rolled trans- lucent film Ex. 29 Vistomer 0.3667 0.381 5670Smooth, WT — HD2800, thick, rolled trans- parent film Ex. 30 Coathylene0.22 0.2152 10000 Smooth,  97 103.1 NC5374 trans- rolled parent, cracksin groove after test Ex. 31 Coathylene 0.2077 0.2134 10000 Smooth, 126 79.4 NB6454 trans- rolled parent puddles Ex. 32 Coathylene 0.44990.5867 6390 Smooth, WT — HO1681 trans- rolled parent, thin Ex. 33Coathylene 0.4486 0.4526 62 Smooth,  68  0.9 HA2454 trans- rolledparent, puddles Ex. 34 Coathylene 0.3389 0.4275 1240 Smooth, 348  3.6HA1931 trans- rolled parent, puddles Ex. 35 Coathylene 0.3545 0.40164259 Fairly 140  30.4 PB0580 thick, rolled uniform, rough Ex. 36Coathylene 0.4386 0.4778 180 Smooth, 113  1.6 PB0580 trans- parent Ex.37 Coathylene 0.2046 0.3029 3108 Smooth,  78  39.8 PY0787 thick, rolledtrans- parent film Ex. 38 Hostalen 0.296 0.3298 10000 Medium  87 114.9GHR8020/ thickness, MoS₂ uniform, 100/6.5 rough rolled Ex. 39 Microscrub0.5217 0.5225 63 Thin,  59  1.1 50/ MoS₂ mottled 100/6.5 Ex. 40Microscrub 0.3884 0.3818 10000 Moderately 121  82.6 50/ thin, Hostalentrans- GHR8020/ lucent MoS₂ rolled Ex. 41 NB6454/ 0.2061 0.2351 10000Thick,  42 238.1 GHR8110 uniform, 25/75 rough rolled Ex. 42 Coathylene0.2438 0.2512 10000 Thick,  66 151.5 NC5374/ uniform, GHR8110 rough25/75 rolled Ex. 43 Coathylene 0.2538 0.2613 10000 Thick,  89 112.4NC5374/ uniform, GHR8110 rough 50/50 rolled Ex. 44 Coathylene 0.19450.217 10000 Thick,  40 250.0 NB6454/ uniform, Hostalen rough GHR811050/50 rolled Ex. 45 Coathylene 0.2515 0.2816 10000 Thick,  83 120.5NC5374/ uniform, GHR8110 rough 75/25 not rolled Ex. 46 Hostalen 0.27240.2575 10000 Thick, 115  87.0 GHR8110 uniform, not rolled rough Ex. 47Coathylene 0.2227 0.2165 10000 Thick,  45 222.2 NC5374/ uniform, GHR8110rough 25/75 not rolled Ex. 48 Coathylene 0.2136 0.246 10000 Thick,  76131.6 NC5374/ uniform, GHR8110 rough 38/62 not rolled Ex. 49 Coathylene0.3462 0.3431 5100 Bumpy WT — NC5374 not rolled Ex. 50 Coathylene 0.27820.2847 10000 Thick, 209  47.8 NC5374/ uniform, GHR8110 rough 75/25 notrolled Ex. 51 Coathylene 0.2136 0.2182 10000 Thick,  73 137.0 NC5374/uniform, GHR8110 rough 50/50 not rolled

[0107] The coatings of the Examples show reduced coefficients offriction in comparison to the comparative Example. In particular, thecoatings of Examples 9, 10, 11, 13, 14b, 14/18, 15-17, 19 21, 22, 23b,have significantly reduced coefficients of friction and show good wearcharacteristics. When the Versicoat polyurethane control coating isfresh, the wear resistance is typically about 400 cycles/micron.However, with weathering, the wear resistance typically drops to about10 cycles/micron, and the coefficient of friction greatly increases.

[0108] Thus, a reduced coefficient of friction is obtained with thecoated substrates of the present invention. The wear resistance of thecoating containing a polyethylene polymer having a molecular weight of300,000 and higher, Examples 13 to 17 is greater than coatingscontaining polyethylene with a molecular weight below 300,000, such asExamples 30 and 31 However, the adhesion of the ultra high molecularweight HDPE to the substrate is typically not as strong as with theother HDPE.

[0109] Surprisingly, the coating which is a mixture of the of ultra-highmolecular weight HDPE and the lower-molecular-weight HDPE has improvedwear resistance and satisfactory adhesion to the substrate.

[0110] The coated substrate prepared in example 14, employed apolyethylene polymer having a molecular weight in excess of 6,000,000,GUR 400F. The resulting laminate had poor adherence making it lesspreferred for a vehicle seal but useful for a laminate having atemporary or easily removable polyolefin coating.

[0111] Crystalline polyolefin powders were also applied to rubbersubstrates having a temperature in the range of 20° C. to 26° C.; thecoatings were satisfactory based on visual evaluation.

What is claimed is:
 1. A method of coating polyolefin rubber substratecomprising the following steps: a. providing a crystalline polyolefinpowder comprising a crystalline polyolefin polymer having weight averagemolecular weight of from 30,000 to 10,000,000 and a degree ofcrystallinity of 20 wt. % to 100 wt. %; b. applying a crystallinepolyolefin powder, to the polyolefin rubber substrate, in an amountsufficient to form a continuous layer when melted; and c. then meltingthe crystalline polyolefin powder to form a continuous, fused,polyolefin coating disposed on, and adherent to, the polyolefin rubbersubstrate.
 2. The method of 1, further comprising the step of:compressing the molten polyolefin coating.
 3. The method of 1, whereinthe polyolefin polymer has a an average particle diameter of from 5 to600 μm and a melt flow index above from 0.0 to 500 g/10 minutes, at 190°C. under a load of 21.6 kg., and the rubber substrate is selected fromthe group consisting of: ethylene propylene diene terpolymer, ethylenepropylene rubber, butyl rubber, chlorobutyl rubber, and bromobutylrubber, and mixtures thereof.
 4. The method of claim 3, wherein thecrystalline polyolefin powder comprises a powdered polyethylenecomprising at least one high density polyethylene polymer.
 5. The methodof claim 3, wherein the crystalline polyolefin powder comprises apowdered polypropylene polymer.
 6. The method of 3, wherein, wherein thecrystalline polyolefin polymer comprises isotactic polypropylene.
 7. Themethod of claim 3, wherein the crystalline polyolefin powder comprises:from 10 to 90 parts by weight of powdered high-density polyethylenepolymer, having a weight-average molecular weight from 300,000 to10,000,000 g/mol.; and from 10 to 90 parts by weight of powderedhigh-density polyethylene polymer, having a weight-average molecularweight from 40,000 to 150,000 g/mol.
 8. The method of claim 6, whereinthe rubber substrate is ethylene propylene diene terpolymer.
 9. Themethod of claim 3, wherein the crystalline polyolefin powder comprises:from 25 to 75 parts by weight, of the powdered high-density polyethylenepolymer, having a weight-average molecular weight from 600,000 to6,000,000 g/mol.; and from 25 to 75 parts by weight of powderedhigh-density polyethylene polymer, having a weight-average molecularweight from 40,000 to 150,000 g/mole.
 10. The method of claim 4, whereinthe average particle diameter of the crystalline polyolefin powder isfrom 30 to 350 μm.
 11. The method of 4, wherein the polyolefin polymerhas a weight average molecular weight of from 30,000 to 6,000,000. 12.The method of claim 9, wherein the rubber substrate is ethylenepropylene diene terpolymer.
 13. The method of claim 3, wherein therubber substrate has a glass run channel therethrough and thecrystalline polyolefin powder is disposed in the glass run channel andthe polyolefin coating has an average coefficient of friction againstglass of less than 0.5 and a wear resistance of at least 30 cycles permicrometer as measured using glass having with satin edge, under a 2.7kg load.
 14. The method of claim 13, wherein the polyolefin coating hasan average coefficient of friction against glass of less than 0.4 and awear resistance of at least 100 cycles/gm as measured by using glasshaving with satin edge, under a 2.7 kg load.
 15. The method of claim 14,wherein the average particle diameter of the powdered polyolefin is from90 to 250 μm.
 16. The method of claim 14, wherein the polyolefin coatinghas a wear resistance of at least 200 cycles/μm as measured by usingglass having with satin edge, under a 2.7 kg load.
 17. The method ofclaim 14, wherein the polyolefin coating has a wear resistance of atleast 300 cycles/μm as measured by using glass having with satin edge,under a 2.7 kg load.
 18. The seal of claim 14, wherein the polyolefincoating has an average thickness of 10 μm to 3 mm.
 19. A vehicle sealcomprising: an rubber body having a glass run channel therethrough, saidchannel defined by glass-contacting surfaces of the rubber body; and acontinuous coating of fused polyolefin disposed on at least a portion ofthe glass contacting surfaces and adherent to the polyolefin rubberbody; said coating comprising a crystalline polyolefin polymer havingweight average molecular weight of from 30,000 to 10,000,000 and adegree of crystallinity of 20 wt. % to 100 wt. %.
 20. A laminatecomprising: an polyolefin rubber substrate; and a continuous coating offused polyolefin disposed on and adherent to the polyolefin rubbersubstrate said coating comprising a crystalline polyolefin polymerhaving weight average molecular weight of from 30,000 to 10,000,000 anda degree of crystallinity of 20 wt. % to 100 wt. %.